1. Field of the Invention
This invention relates to and has among its objects novel apparatus and methods for providing packed red blood cells (erythrocytes) which are substantially free of platelets and contain low levels of white cells and have a storage life of up to about 35 days. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.
2. Description of the Prior Art
It is desirable, for patients who require frequent blood transfusions, to remove white cells and platelets from donor blood prior to transfusion. Febrile reactions, which are usually attributable to transfused HLA antigens on white cells and platelets present in the blood may occur in 3.6% of patients infused. Such side effects are usually more frequent and severe in patients who receive multiple transfusions.
The removal of HLA antigen may be accomplished in a number of ways. Perhaps the most effective means, but unfortunately the most costly, involves the reconstitution of frozen blood.
A less expensive approach is to wash blood with saline in a number of washes. However, this saline wash approach is time consuming not only in the processing of batches but also in continuous operation. Furthermore, significant loss of red cells occurs and less predictable removal of white cells and platelets is obtained.
Kikugawa et al in Vox Sang., Vol. 34, 281-290 (1975) describe commercial cotton wool filters for filtering blood to remove the above HLA antigen. These filters are, however, expensive and cumbersome to use.
Diepenhorst et al in Vox Sang., Vol. 23, 308-320 (1972) and Vol. 29, 15-22 (1975) disclose cotton wool filtration of blood under pressure. This method, while efficient, requires a special apparatus that is expensive.
All of the above techniques require that the treated blood be infused within 24 hours of treatment in order to avoid the potential risk of infection. Prolonged shelf life of blood so treated is not possible.